Control system



A. A. PONSONBY.

CONTROL SYSTEM.

APPLICATION FILED AUG.9, 1920.

1 ,37 9 ,693 Patented May 31, 1921.

' WIT ESSES: INVENTOR A0705 IOU/1201796 w ATTORNEY UNITED STATES PATENT OFFICE.

AMOS A. PONSONBY, OF SCRANTON, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8c MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONTROL SYSTEM.

T0 allwhom-z'tmay concern: 7 7

Be it known that I, Amos A. PONSONBY, a citizen of the United States, and a resident of Scranton, in the county of Lackawanna and State of Pennsylvania, have invented a new and useful Improvement in Control Systems, of which the following is a specification.

My invention relates to control systems and particularly to systems for controlling the sequence of operation of a plurality .of electromagnetic switches for governing the operation of dynamo-electric machines.

The object of my invention is to provide a simplified system of the above-designated character.

Figure 1 of the accOInpanying drawing is a diagrammatic view of a control system embodying my invention, and Fig. 2 is a diagrammatic view of a modified form of my invention.

The control system illustrated in Fig. 1 comprises a motorl having a shunt fieldmagnet winding 2 and a starting resistorB, portions of which are adapted to be shunted by a plurality of electromagnetically operated switches at, 5, 6 and 7 The switches 4,

5, 6 and 7 are respectively provided with electromagnet coils 8, 9, '10 and 11 which are energizedfrom an auxiliary resistor 12 having a pluralityof portions 18, 1 1 and 15. The main motor circuit is provided with a current limit relay 16 that is actuated to an open position when the current traversing the motor circuit exceeds a predetermined value. I

The switches, 5 and 6 are respectively provided with pairs of interlocks 17, 18 and 19 which severally shunt corresponding portions of the resistor 12 and complete an en ergizingcireuit-for the actuating coil of the succeeding switch to be actuated. Energy is supplied to the system through main line switch 20.

If it is assumed that the control'systemillustrated in Fig. 1 occupies the position shown, operating circuits for the motor 1 may be established by closing line switch 20, which energizes the shunt field-magnet winding 2 and establishes an operating circuit for the armature of motor 1 and starting resistor 3 in series relation. The initial rush of current through the motor circuit actuates relay 16 to an open position and- Specification of Letters Patent.

Patented May 31, 1921. Serial No. 402,296.

thereby inserts the resistor 12 in series relation with coil 8 of switch 4. e

The resistor 12 is of such value that the energy supplied to the actuating coil 8 is not sutficient to actuate the switch 45 to its closed position but is of suflicient value to maintain it in its closed position after it has been actuated thereto by a current of higher value.

When the current traversing the motor circuit decreases to a predetermined minimum value, the relay 16 again closes to shunt the resistor 12 from the circuit of actuating coil 8. 'An increased voltage is applied to coil 8 and the switch 4 closes to shunt a portion of the starting resistor 3 from the motor circuit. The interlock 17, which is actuated by switch 4, establishes a circuit for coil 9 and, at the same time, shunts a portion 13 of the resistor '12. The current traversing the motor circuit increases by reason of the reduced resistance in the motor circuit and when a suflicient value to actuate relay 16 is attained, the resistor 12, with portion 13 shunted, is inserted in the circuit of the actuating coils 8 and 9. Since the energy supplied by the resistor is not of suflicient value to actuate switch 5, it will remainopen until the current. traversing the motor circuit again decreases to such degree as to permit relay 16 to close.

.The switch 5 then closes toshunt an additional portion of the starting resistor 3. The interlock 18, which is closed by switch 5, establishes a circuit for actuating coil 10 of switch 6, and shunts anadditional portion 14 of the resistor 12. As soon as the current traversing the main motor circuit again decreases to a predetermined minimum value, relay 16 closes and coil 10 is sufiiciently energized to close switch 6. In the same manner, switch 7 is closedby a circuit. which is established by interlock 19 of switch 6.

The respective interlocks 17, 18 and 19 shunt such portions of the resistor 12 from the energizing circuit for the electromagnet coils 8, 9, 10 and 11 as will maintain a substantially uniform voltage across the coils grouped in parallel circuit relation, so increases the current traversing the resistor 12 that, unless provision were made to shunt portions of the resistor 12 from the energizing circuit, the voltage impressed upon the respective coils would decrease very rapidly as successive coils are connected in the circuit. By shunting portions of the resistor 12 a relatively large number of switches may be governed by means of one resistor and an accelerating relay. The switches, when once closed, are maintained in such positions regardless of the subsequent action of relay 16.

Referring particularly to Fig. 2 of the drawing, switches 5 and 6 are respectively provided with single interlocks 21 and 22. The resistor 12 is provided, in this instance, with a tap for shunting a single portion 13 of the resistor from the circuit. lVith the foregoing exceptions, the system illustrated in Fig. 2 employs apparatus that is similar to the apparatus shown in Fig. 1 and is similarly designated.

To operate the system illustrated in Fig. 2, main line switch 20 is closed to establish a circuit including the armature of motor 1 and the starting resistor 3. The cur rent initially traversing the motor circuit is of sufi'icient value to actuate relay 16 to an open position and thereby insert resistor 12 in circuit with actuating coil 8 of switch 1. When the current traversing the motor circuit decreases to a predetermined minimum value, relay 16 closes and the coil 8 is energized to close switch 4.

lVhen switch a is closed, the interlock 17 completes a circuit for the actuating coil 9 of switch 5 and, also, shunts a portion 13 of the resistor 12 in order to maintain the voltage that is applied to the respective switch-actuating coils of sufiicient value to maintain the switches in their closed positions when the resistor 12 is inserted in the energizing circuit for the coils by relay 16.

The increased current that is caused to traverse the motor circuit by the closure of switch 4: again lifts relay 16 and switch 5 is maintained in its open position until the current decreases to such degree as to permit relay 16 to shunt resistor 12 from the energizing circuit for coil 11. Switch 5 shunts an additional portion of starting resistors. The interlock 21, which is actuated by switch 5, establishes an energizing circuit for coil 10 of switch 6. Relay 16 again operates to close switch 6 in the manner hereinbefore described for switch 5. The interlock 22 completes a circuit for actuating coil 11 of switch 7. Switch 7 is now controlled by relay 16 and it closes to completely shunt starting resistor 3 from the motor circuit.

It will be noted that, in the system illustrated in Fig. 2, a single portion of the resistor 12 is shunted whereas, in the system of Fig. 1, several portions of the resistor are shunted. It has been found that, although the former system does not operate to maintain the uniform value of coil voltage when relay 16 is open, the system illustrated in Fig. 2 provides means for controlling a greater number of switches than have heretofore been operated from a single resistor.

Although the systems hereinbefore described are employed for operating electric motors, the principles embodied in my invention may be employed for operating any electric apparatus requiring a plurality of contactors actuated in accordance with certain electrical conditions and in a given sequence. The order in which the contactors are closed is controlled by arranging the interlocks on the respective switches in accordance with the desired sequence.

Although I have described a simple and preferred form of my invention, it will be understood that modifications are possible, and I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A control system comprising a plurality of electromagnetically controlled switches, a resistor in circuit with the actuating coils of certain of said switches for preventing the actuation thereof, a relay adapted to effect the operation of said switches by temporarily establishing a circuit in shunt relation with said resistor under predetermined conditions, and interlocking means associated with said switches for controlling the sequence of operation thereof and for establishing shunt circuits for portions of said resistor.

2. A control system comprising a main circuit, a plurality of electromagnetirally controlled switches for controlling said main circuit, a resistor in circuit with the actuating coils of said switches, means dependent upon the current traversing said main circuit for completely shunting said resistor, and means associated with said switches for shunting portions of said resistor.

3. A control system comprising a main circuit, a plurality of electromagnetically controlled switches for controlling said main circuit, a resistor in circuit with the actuating coils of said switches, means dependent upon the current traversing said main circuit for temporarily shunting said resistor, and means associated with said switches for permanently shunting portions of said resistor.

1. A system of control comprising a main circuit, a plurality of switches for controlling said main circuit, a resistor in circuit with the actuating coil for said switches, means responsive to current conditions in said main circuit for temporarily shunting the whole of said resistor, and means associated with said switches for shunting portions of said resistor in accordance with the number of switches closed and for establishing an energizing circuit for other of said switches.

5. A control system comprising a main circuit, a plurality of switches for controlling said main circuit, a resistor in circuit with the actuating coil for said switches, means responsive to current conditions in said main circuit for shunting the whole of said resistor, and means associated with said switches for shunting portions of said resistor and for establishing energizing circuits for other of said switches.

6. The combination with a dynamo-electric machine and a subdivided resistor in circuit therewith, of a plurality of switches for successively short-circuiting sections of said resistor and severally having actuating coils, a translating device in circuit with said coils and means for excluding portions of said translating device from circuit as said resistor sections are short-circuited.

7. The combination with a starting resistor for an electric motor, of a plurality of shunting switches associated therewith and severally having actuating coils and an auxiliary resistor in circuit with said coils and adapted to be gradually shunted simultaneously with said starting resistor.

8. The combination with an electric motor and astarting resistor therefor, of an auxiliary resistor and a plurality of switches in circuit with said starting resistor and severally having actuating coils in circuit with said auxiliary resistor, said switches upon closing being adapted to concurrently shunt portions of both resistors.

9. The combination with a starting resistor for an electric motor, of an auxiliary resistor and a plurality of switches in circuit with said starting resistor and severally having actuating coils in circuit with said auxiliary resistor, said switches upon closing being adapted to shunt portions of said starting resistor and concurrently connect the actuating coil of the succeeding switch in active circuit relation with successively decreasing portions of said auxiliary resistor.

10. The combination with an electric motor and a starting resistor therefor, of a plurality of switching devices for shunting portions of said resistor to accelerate said motor and severally having actuating coils, an auxiliary resistor in circuit with said coils, and means for shunting portions of said auxiliary resistor as the motor'is accelerated and concurrently connecting another of said actuating coils in active circuit relation with the remaining portion of that resistor.

In testimony whereof, I have hereunto subscribed my name this 19 day of July,

AMOS A. PONSONBY, 

